A discharge device called a dispenser is used in many cases to apply a liquid material along a predetermined pattern in a process of manufacturing electronic devices. The dispenser is widely used in manufacturing various devices ranging from large-sized devices to small-sized devices. For instance, the dispenser is used in a step of linearly applying a phosphor or an adhesive onto a flat panel display represented by a liquid crystal or organic EL display, or in a step of linearly applying an adhesive for fixing a smartphone cover along an outer periphery of the cover.
Application work using the dispenser is performed by discharging a liquid material from the dispenser while the dispenser and a worktable are relatively moved in accordance with a predetermined application pattern. However, when a line drawing application is performed for the application pattern including a corner portion, a problem occurs in that a relative moving speed between the dispenser and the worktable is changed and a line width of a drawn application line varies in the corner portion (i.e., a problem that, in spite of desiring a line to be applied in the corner portion in the same width as that in a linear portion as illustrated in FIG. 10(A), the line in the corner portion becomes wider than in the linear portion as illustrated in FIG. 10(B) due to change of the relative moving speed between the dispenser and the worktable in the corner portion).
In consideration of the above problem, there has been proposed a technique of applying a proper amount of the liquid material in the corner portion by decelerating the relative moving speed between the dispenser and the worktable and reducing a discharge pressure of the dispenser at a start point of the corner portion, and then accelerating the relative moving speed between the dispenser and the worktable and increasing the discharge pressure of the dispenser before reaching an end point of the corner portion.
However, because the discharge pressure (discharge amount) is controlled in accordance with pattern data stored in a microcomputer, programming is needed with respect to the following points to realize the desired line drawing application in an application apparatus that includes, for example, a robot (XYZ-direction moving device) to relatively move the dispenser and the worktable.
Programming is first needed with respect to a relative movement command for relatively moving the dispenser and the worktable in accordance with the application pattern. Programming is further needed with respect to a discharge amount control command for controlling the discharge amount at each application position on the application pattern. The discharge amount control command is, for example, a command for weakening an air pressure for the discharge, shortening a distance between an annular valve seat in communication with a discharge port and a valve member, or reducing a rotation speed of a screw that gives a discharge propulsion force. Furthermore, in a place where the relative moving speed is changed as in the corner portion, it is needed to divide a locus of the line drawing in the corner portion into a plurality of parts, and to carry out programming with respect to each of the relative moving speed and the discharge pressure for each part of the divided locus.
Because the task of programming the discharge amount at each application position takes time and effort, there is proposed a technique of automatically controlling the discharge pressure (discharge amount) in accordance with the change of the relative moving speed between the dispenser and the worktable.
For example, Patent Document 1 discloses a technique of controlling a liquid amount applied to an object to be kept constant by opening a valve rod to increase a discharge flow rate when a linear moving speed of a liquid application apparatus body is high, and conversely by closing the valve rod to decrease the discharge flow rate when the linear moving speed of the liquid application apparatus body is low.
Furthermore, Patent Document 2 discloses a technique of preparing, in a conversion unit, a relational expression or a conversion table representing a relation between a moving speed of a dispense head and a control amount of a discharge amount control device, and calculating the control amount to realize a preset line width by putting the moving speed into the relational expression or the conversion table.